JP2002540839A - Endodontic device, device blank and method of manufacturing the same - Google Patents

Abstract

An endodontic treatment including an elongated member having a longitudinal axis (44a), a proximal end, a distal end, and a working length (22) between the proximal and distal ends. Instrument (10). The working length (22) is formed by a plurality of surfaces (24, 26, 28, 30) cut from its outer surface along a path extending at least partially around the longitudinal axis (44a). Is done. The cut surfaces (24, 26, 28, 30) are then physically twisted to form a helical cutting and / or debris removal edge (32, 34) extending around the longitudinal axis (44a). , 36, 38). The device (10) may be a file or reamer used in root canal treatment, and may have three, four or more longitudinally extending surfaces and corresponding edges. The cutting edge defines a grinding angle (α) that varies along the working length (22). The flexibility of the device (10) may also be easily changed according to the invention. The method of making the instrument includes grinding flats on the outer surface of the wire blank (44), which flats are twisted about a portion of the longitudinal axis (44a). The blank (60) having partially twisted flats (24,26,28,30) is then physically twisted to form a spiral cutting and / or debris removal edge (32,34,30). 36, 38) are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

FIELD OF THE INVENTION The present invention relates generally to endodontic devices such as files and reamers, in particular
It relates to a device that is particularly effective in root canal treatment.

[0002] Endodontists use various types of devices to clean and dilate the root canal of a tooth. In general root canal treatment, an endodontic physician first creates an opening in the surface of the tooth to make it accessible. The endodontist then uses a small instrument such as a handheld file and reamer to clean the narrow, tapered root canal,
Let it expand. In a conventional procedure, the endodontist fills the prepared root canal with gutta-percha, a rubbery substance, and then seals the teeth with protective cement.
The endodontic physician may apply a crown to the tooth as a last step.

In general, endodontists use a series of sophisticated and flexible files to clean and shape the root canal. Each file includes a proximal end, and generally includes a handle and a distal end or tip that is grasped between the endodontist's fingers. A working length having a twist groove and a cutting edge is disposed between the proximal end and the distal end. Endodontists,
Use a larger diameter file to continuously increase the diameter of the root canal to achieve the desired diameter and shape.

[0004] Endodontic root canal files and reamers are generally formed from three differently shaped twisted blanks. One type is formed by twisting a grinding blank having a square cross section to form four helical cutting edges per revolution. Another type consists of a twisted blank of triangular cross section with three cutting edges per revolution. A third type, often referred to as the K-flex type, is formed from a blank having a parallelogram-shaped cross-section, such as a diamond-shaped cross-section. After twisting a blank of this type, two cutting edges and two debris removal edges are formed per revolution. All three types of instruments have a tapered large diameter or cross-sectional dimension and a tapered small diameter or cross-sectional dimension, and their taper angles are about the same. Also, the angle formed between the surfaces forming the cutting and debris removal edges is constant along the length of the device.
In other words, the predetermined grinding angle of the edge of the tool is the same along the entire working length of the tool.

[0005] Existing endodontic files and reamers formed from twisted blanks are designed such that the small diameter is purely a function of the large diameter. The undesirable consequences of this type of design are greater for instruments having a greater taper along the working length. In particular, these instruments become more rigid towards the proximal end or handle of the instrument. This makes it difficult to operate within a curved root canal because the instrument does not bend sufficiently to conform to the shape of the root canal. While certain torsionally root canal treatment devices have been completely formed by grinding to achieve more constant flexibility along their length, these devices have significant drawbacks. First, tools that are completely formed by grinding are expensive to manufacture. Also, the twisted instrument can be formed in a wide variety of cross-sectional shapes, depending on the shape of the initially ground wire blank.

[0006] In view of the problems in the art, including those mentioned above, one of the diameters or cross-sectional dimensions, such as a file or reamer formed from a twisted blank, may vary the flexibility, strength and strength of the device. It would be desirable to provide a root canal treatment device that is formed independently of the other diameter or cross-sectional dimension to optimize other working characteristics. In this way, a larger tapered device can provide greater flexibility for operation within a curved root canal and retain sufficient strength to withstand breakage during use.

SUMMARY OF THE INVENTION [0007] The present invention provides, for example, a file, a reamer or other cutting, molding, or cleaning with an elongated member having optimal flexibility, strength and other operating characteristics. An endodontic device, such as a device, is provided. The elongate member includes a longitudinal axis, which is preferably straight when not in use, a proximal end, a distal end, and a working length generally between the proximal and distal ends. The working length is formed with an outer surface having a plurality of twisted or bent surfaces defining at least one cutting edge formed at the junction between adjacent surfaces. The adjacent surface portions are both preferably cut from the outer surface along a longitudinal axis and along a path extending at least partially around the longitudinal axis. There may be at least one twisted surface or a plurality of twisted surfaces on a blank ground according to the present invention. These cut surfaces are physically further twisted to form a helical cutting edge that extends around the longitudinal axis.

[0008] The adjacent surfaces, in accordance with one aspect of the invention, form a cutting edge or debris removal edge having an angle that varies along the working length. Preferably, the angle formed at each edge decreases in the direction from the distal end to the proximal end. This creative aspect is useful for the device in some embodiments. For example, even when the taper is large, the device is more flexible than a conventional device of the same taper. Also, the one or more cutting edges are sharper at the proximal end of the working length, because the angle between adjacent surfaces at this location is smaller. This allows the proximal end to be a more efficient cutter at that portion of the tooth that requires the greatest amount of material removal. Finally, this creative feature also increases the area for debris removal at the proximal end.

The invention also allows the small diameter and the large diameter of the device to be formed in sizes that are distinct from each other. This feature allows the large diameter or cross-sectional dimension to include a taper, while keeping the small diameter or cross-sectional dimension substantially constant along the working length. Thus, a twisted instrument according to this aspect of the invention has a more constant flexibility along the working length, despite the large taper present along the large diameter. Other embodiments of this general feature are also possible, including forming small and large diameters with different tapers.

The endodontic device of the present invention may form many different cross-sectional shapes. Generally, the elongate member of the finished device will have three or four longitudinally extending surfaces and a corresponding number of longitudinal helical edges. The elongated member may be formed from a material having superelastic properties and / or other materials such as titanium, carbon steel or stainless steel.

[0011] A preferred method of manufacturing an endodontic device according to the present invention is to provide an external surface of the wire blank in at least a first path extending along the longitudinal axis of the wire blank and twisting at least partially about the longitudinal axis. After which the one end of the wire blank is twisted relative to the other end and about the longitudinal axis to form at least one helical cutting edge along the working length. Including forming. At least two adjacent surface portions may be cut or ground from the outer surface of the wire blank in first and second paths extending along a longitudinal axis of the wire blank and twisting at least a portion of the longitudinal axis. preferable. For example, a three-sided endodontic device may be formed from a blank ground to have two partially twisted outer surfaces and one straight or axially extending outer surface.
As another example, a four-sided instrument may form four flats that extend longitudinally and are partially twisted and ground. It will be appreciated that the one or more ground surfaces may be flat or have other shapes, such as a concave shape. In a preferred embodiment, the twisted surface of the blank is first ground to twist about 2 ° to about 60 ° about the longitudinal axis along the working length. The working length can be formed in various lengths depending on the intended use of the instrument.

[0012] Other features, objects, and advantages of the invention will be more readily apparent to those skilled in the art when considering the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown the use of an endodontic appliance 10 constructed according to a preferred embodiment of the present invention during root canal treatment of a tooth 12. I have. Teeth 12 include root canals 14,16 and an upper interior 18 that is initially opened using another instrument such as a drill (not shown). The instrument 10 includes, for example, a handle 20 that is manually grasped by an endodontic physician, and a working length 22 having a twist groove, described in more detail below. These devices are generally manually operated, but the invention is also applicable to power operated devices. In a normal mode, the device 1
0 allows the root canal physician to rotate in the direction of arrow “A” and reciprocate in the direction of arrow “B” to clean and dilate the root canal 16.

As shown in the enlarged view of the working length 22 of FIG. 2, each groove has a twisted surface 24,
26, 28, and 30. These surface portions 24, 26, 28, 30
Are formed between the respective edges 32, 34, 36, 38. The smaller diameter or cross-sectional dimension “d” and the larger diameter or cross-sectional dimension “D” are evident along the working length 22 as further shown in FIG. 2 and described in more detail below. The small diameter “d” maintains a substantially constant state along the working length 22, and the large diameter “D”
It is preferable that the size of the first portion gradually increases in a direction extending from the distal end portion 40 to the proximal end portion.
Since the small diameter “d” extends substantially constant along the working length 22, the flexibility of the working length 22 is maintained substantially constant along the working length 22. As also described below, the small diameter “d” may have a taper such that the diameter increases slightly from the distal end 40 to the proximal end 42. However, the size of the taper is preferably substantially smaller than the size of the large diameter "D" taper. For example, the size of the taper for the smaller diameter "d" may range from 0 to about 0.06, and the size of the taper for the larger diameter "D" may range from about 0.02 to about 0.14. .

FIGS. 3A to 3F show a preferred method of manufacturing the device 10. At this point, the cylindrical wire 44 has a tip that is first ground to a sharp tip. The wire 44
It can be formed from any suitable material used in this type of endodontic device. In some examples, these materials include a superelastic material such as NiTi or other materials such as titanium, carbon steel or stainless steel. A grinding wheel 48 is used to continuously grind four longitudinally extending and partially twisted surfaces along the wire 44. In particular, as shown in the end view of the wire 44 in FIGS. 3A and 3B, the grinding wheel 48 rotates as the wire 44 translates along its central axis 44a. At the same time, the wire 44 preferably rotates by an angle α between about 2 ° and about 60 °. This forms the surface part 30.

In a preferred embodiment, for example, the wire 44 is between about 4 mm and about 23 m
can be ground along a working length of m. The wire 44 is driven at a speed of about 100 inches (about 2.54 m) / min depending on the material and size of the wire 44.
Translate along 8. At the same time, the wire 44 is preferably rotated at a constant speed about an angle of about 2-60 ° about its central axis 44a until it reaches the position of the proximal end of the working length shown by the solid line in FIGS. Rotate clockwise. During each grinding operation, as the wire 44 translates over the grinding wheel 48, the grinding wheel 48
Depending on the translation speed of the wire described above and the desired taper, about 0.5 inches (about 1.
It moves in a direction away from the central axis 44a of the wire 44 at a preferred speed of 3 cm) / min. This speed can be varied for different surfaces. The cutting depth may be about 0.005 inches (about 0.13 mm) depending on the size and material of the instrument, and preferably the initial wire diameter is 0.041 inches (about 1.04 mm). .

To form a quadrilateral shape, wire 44 is indexed by 90 ° and the same procedure is used to form another surface 26 shown in FIG. 3C. However, FIG.
As shown at C, the wire 44 rotates counterclockwise during grinding. As shown in FIG. 3D, a third surface portion 28 is formed after the next 90 ° indexing, and as shown in FIG. 3E, a fourth surface portion 26 is similarly formed after the last 90 ° indexing operation. Formed.
In the embodiment described above, the ground blank 60 shown in FIGS. 4, 5 and 6 is formed to be physically twisted by conventional methods until forming the final tool 10 shown in FIG. 2 and I am prepared. One suitable method of twisting is disclosed in US patent application Ser. No. 09/014139, assigned to the assignee of the present invention, the disclosure of which is fully incorporated herein by reference. I have.

As further shown in FIGS. 4, 5 and 6, the ground blank 60 may be substantially constant along the working length 22 or may be slightly inclined as shown in FIG. It has a small diameter "d". The large diameter "D" shown in FIG. 5 is more inclined as shown by dimensions T1, T2, T3. As further shown in FIG. 7, each surface portion 24,
26, 28, 30 gradually widen from the distal end portion 40 toward the proximal end portion 42,
A portion of the ground blank 60 is twisted about the axis 44a. The cross-section of the ground blank 60 of this embodiment changes from a relatively square cross-section near the distal end 40 to a rhombic cross-section at the proximal end 42. 6, the edges 34,
38 is sharper at the proximal end 42 than at the distal end 40. The distal end 40 may have a rhombic cross section, but the rhombic shape of the distal end 40 is not as exaggerated as the proximal end 42. The ground blank 60, once formed, is assigned to the assignee of the present invention and is disclosed in US patent application Ser. No. 09/014139, the disclosure of which is fully incorporated herein by reference. It can be twisted in a conventional manner, such as the embodiment described.

FIGS. 8A to 8D show the grinding process used for an exemplary three-sided tool made in accordance with the present invention. In particular, as shown in FIGS. 8A and 8B, the wire 100 is already ground near the tip 102 to form a sharp tip. Alternatively, the wire is preferably cylindrical. The wire 100 is then placed close to the grinding wheel 104 in a manner similar to the first embodiment. The grinding wheel 104 is used for continuously grinding three surface portions 106, 108, 110 extending in the longitudinal direction.
In this embodiment, only the surfaces 106 and 108 are ground to provide a partially twisted surface as described above in connection with the first embodiment. The surface portion 110 is a straight inclined surface portion that is not twisted around the central axis 100a of the wire 100. More specifically, as shown in the end view of the wire 100 in FIGS. 8A and 8B, the grinding wheel 104 rotates as the wire 100 translates along the central axis 100a. At the same time, the wire 100 is preferably about 2 ° to about 60 °
Rotate by an angle θ between. Other parameters such as working length dimensions, translational movement speed, and rotation speed of wire 100 may be as described above in connection with the first embodiment. The speed and the cutting depth when the grinding wheel 104 moves away from the center axis 100a may be substantially the same as those described in relation to the first embodiment.

To form the second surface 108, the wire 100 is indexed by 120 ° and the same procedure is used to grind the surface 108 as shown in FIG. 8C. FIG. 8C
As shown in Figure 2, the wire 102 rotates counterclockwise during the grinding process instead of clockwise. This forms a cutting edge 112 defined between the surface portions 106 and 108, which preferably has the same general properties as the cutting edges 34, 38 formed in the first embodiment. .

As shown in FIG. 8D, the third surface portion 110 is formed after the next 120 ° indexing step. However, this surface 110 is not a twisted surface, and thus the wire 100 does not rotate when the surface 110 is ground with the grinding wheel 104. Instead, the wire 100 translates axially with respect to the grinding wheel 104 when the grinding wheel 104 moves away from the center axis 100a to form a desired taper away from the tip 102. I do. Thus, this last grinding operation forms two debris removal edges 114, 116 defined between the surface portions 106, 110 and 108, 110.

The ground blank 120 thus formed is best shown in FIGS. As best understood from the discussion of FIGS. 9 and 12,
The cutting edge 112 becomes sharper along the direction from the tip 102 to the portion 122 closer to the base (FIG. 12). The triangular cross-sectional shape of the ground blank 120 changes from a more equilateral triangular shape near the tip 102 to a portion 12 closer to the base.
It may change to an isosceles triangle more toward 2. The blank 120 is preferably twisted until the device 130 is formed using conventional methods, for example, as shown in FIG. Due to the relatively large angle between each surface portion 106, 110 and 108, 110, the edges 114, 116 remove debris, for example, rather than cutting tissue during endodontic treatment, shown generally in FIG. Perform the action of It will be understood that the embodiments of the present invention shown in FIGS. 8-12 are only one alternative embodiment, and that many other alternative embodiments are possible. These alternative embodiments are:
For example, a three-sided ground blank in which each of the three surface portions is at least partially twisted about the axis of the blank, or subsequently physically twisted and twisted at least partially about the axis of the blank. Other polyhedral blanks may be included that include at least one surface portion that has been ground as such.

FIGS. 14-16 illustrate one possible twisting device 140 composed of a three-sided blank that can be formed by the method shown and described in connection with FIGS. 8A-8D.
5 shows two alternative embodiments. More specifically, the instrument 140 includes two surfaces 142, 144 ground to form a twist at least in part, and a third surface 146 having a straight angled ground. The difference between this embodiment and the previous embodiment essentially includes the physical properties of the three-sided blank. For example, the taper along the length of the instrument 140 is more exaggerated in the embodiment of FIG. 14 as compared to FIG. Further, the number of twists is small in the embodiment of FIG. Although more exaggerated, it will again be appreciated that the instrument 140 has a cross-sectional shape closer to an equilateral triangle at the distal end (FIG. 16) than at the more elongated triangular proximal end (FIG. 15). . As in the second embodiment, the instrument 140 includes a cutting edge 148 formed between the surfaces 142,144. The remaining two edges 150, 152 essentially act as debris removal edges.

Although the present invention has been shown and described in some detail by way of description of preferred embodiments, it is to be understood by the applicant that the appended claims limit their scope to this description or in any way. Not an intention. Other advantages and modifications will be readily apparent to those skilled in the art. This specification describes the invention together with the currently known preferred methods of practicing the invention. However, the invention itself should only be defined by the appended claims.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an endodontic device according to the present invention in use within a tooth and a root canal.

FIG. 2 is an enlarged elevation view of a portion of the endodontic device shown in FIG.

FIG. 3A is an end view of the first step of the grinding process used to form the endodontic device of FIGS. 1 and 2;

FIG. 3B is a view similar to FIG. 3A, but showing the wire blank rotating during the grinding process.

FIG. 3C is a view similar to FIGS. 3A and 3B, but illustrating a grinding process for a second surface portion.

FIG. 3D is similar to FIGS. 3A to 3C, but illustrates a grinding process for a third surface portion.

FIG. 3E is a view similar to FIGS. 3A to 3D, but illustrating a grinding process for a fourth surface portion.

FIG. 3F is a side view along the line 3F-3F in FIG. 3E.

FIG. 4 is a partial side view showing the small diameter of the blank ground according to FIGS. 3A to 3E.

FIG. 5 is a cutaway side view showing a large diameter of the blank shown in FIG. 4;

FIG. 6 is an end view of the blank ground according to FIGS. 3A to 3E.

FIG. 7 is a perspective view of a blank ground according to FIGS. 3A to 3E.

FIG. 8A is an end view of the first step of the grinding process used to form a blank for a three-sided endodontic device constructed in accordance with the present invention.

FIG. 8B is a view similar to FIG. 8A, but showing the blank rotating during the grinding process.

8C is a view similar to FIGS. 8A and 8B, but showing a second surface portion partially twisted. FIG.

8D is a view similar to FIGS. 8A to 8C but showing a straight third surface. FIG.

FIG. 9 is an end view of a three-sided blank ground in accordance with the present invention.

FIG. 10 is a cutaway side view along the line 10-10 of FIG. 9, showing the small diameter of the blank.

FIG. 11 is a cutaway side view, along the line 11-11 of FIG. 10, showing the large diameter of the blank.

FIG. 12 is a perspective view of a three-sided blank ground according to FIGS. 8A to 8D.

FIG. 13 is a cutaway elevation view of the twisting instrument formed from the three-sided blank of FIG.

FIG. 14 is a cutaway elevation view of an alternative endodontic device twisted from a three-sided blank.

FIG. 15 is a sectional view taken along lines 15-15 of FIG. 14;

16 is a sectional view taken along lines 16-16 of FIG.

────────────────────────────────────────────────── ─── [Continuation of summary] Yes. The blank (60) having a partially twisted flat (24, 26, 28, 30) is then physically twisted to form a helical cutting and / or debris removal edge (32, 30). 34, 36, 38).

Claims (28)

[Claims] 1. A method of manufacturing an endodontic device from a wire blank having an outer surface, a longitudinal axis, and a working length disposed generally between a proximal end and a distal end, the method comprising: Removing material from an outer surface of the wire blank along at least a first path extending along a directional axis and twisting at least in part about the longitudinal axis; at least one of a proximal end and a distal end; And twisting about a longitudinal axis to form at least one helical cutting edge along the working length. 2. An outer surface of the wire blank prior to twisting the wire blank along at least a second path extending along a longitudinal axis of the wire blank and twisting at least partially about the longitudinal axis. 2. The method of claim 1, further comprising removing material from the. 3. The method of claim 2, further comprising: prior to twisting the wire blank, removing material from an outer surface of the wire blank along at least a third path extending along a working length. Way. 4. The method of claim 3, wherein the third passage twists at least partially about a longitudinal axis of the wire blank. 5. The outer surface of the wire blank prior to twisting the wire blank along at least a fourth path extending along a longitudinal axis of the wire blank and twisting at least partially about the longitudinal axis. 5. The method of claim 4, further comprising removing material from the. 6. The method of claim 1, wherein removing the material further comprises grinding a flat surface on an outer surface along the first path. 7. An elongated member including a longitudinal axis, a proximal end, a distal end, a working length, an outer surface disposed generally between the proximal end and the distal end, and grinding from the outer surface. A plurality of longitudinally extending surface portions, wherein at least one of the surface portions is ground and extends along a longitudinal axis and at least a portion of a circumference of the longitudinal axis. The endodontic device further comprises a surface portion that is twisted to form at least one helical cutting edge extending about the longitudinal axis. 8. The endodontic device according to claim 7, wherein at least two of the surface portions are ground to extend at least partially around the longitudinal axis. 9. The endodontic device according to claim 7, wherein at least three of the surface portions are ground to extend at least partially around the longitudinal axis. 10. The endodontic device according to claim 7, wherein at least four of the surface portions are ground to extend at least partially around the longitudinal axis. 11. The endodontic device according to claim 7, wherein the elongated member is formed from a superelastic material. 12. The endodontic device according to claim 11, wherein the superelastic material comprises nickel-titanium. 13. The elongate member is formed from a material including steel.
Endodontic device described in the item. 14. An elongated member including a longitudinal axis, a proximal end, a distal end, a working length, and an outer surface disposed generally between the proximal end and the distal end; A plurality of helically twisted and longitudinally extending surfaces on an outer surface of the ridge, and a first helical cutting edge formed at a junction between adjacent surfaces, the first helical cutting edge comprising: The endodontic device wherein the cutting edge is defined by an angle between said adjacent surfaces that varies along a working length. 15. The endodontic device according to claim 14, wherein the angle decreases in a direction from the distal end toward the proximal end. 16. The helical torsion and three longitudinally extending surfaces forming the first helical cutting edge, and further comprising three working surfaces varying along a working length. 16. The endodontic device according to claim 15, wherein the device also forms a second helical cutting edge defined by an angle between two of the portions. 17. The endodontic device according to claim 16, further comprising four surface portions which are spirally twisted and extend in a longitudinal direction. 18. The apparatus according to claim 18, further comprising three helically twisted and longitudinally extending surfaces forming said first helical cutting edge, said three surfaces varying along a working length. 15. The endodontic device according to claim 14, wherein the endodontic device also forms a second helical cutting edge defined by an angle between two of the portions. 19. The endodontic device according to claim 18, further comprising four surface portions that are spirally twisted and extend in a longitudinal direction. 20. The elongate member is formed from a superelastic material.
Endodontic device described in the item. 21. The endodontic device according to claim 20, wherein the superelastic material comprises nickel-titanium. 22. The elongate member is formed from a material including steel.
4. The endodontic device according to item 4. 23. A blank used in the manufacture of an endodontic device, wherein the blank includes a longitudinal axis and includes a proximal end, a distal end, a working length, and a substantially proximal end. An elongate member having an outer surface disposed between the portion and the tip, wherein the working length portion is formed from a plurality of surface portions longitudinally ground from the outer surface, wherein at least one of the surface portions is formed. A blank that is ground along a path that extends along and at least partially around the longitudinal axis. 24. The blank according to claim 24, wherein at least two of the surface portions are ground along a path extending along and at least partially around the longitudinal axis. 25. The blank according to claim 24, wherein three of the surface portions are ground along a path extending along and extending at least partially around the longitudinal axis. 26. The blank of claim 23, wherein at least four of the surface portions are ground along a path extending along and at least partially around the longitudinal axis. 27. The blank according to claim 23, wherein the one surface portion gradually widens in a direction from the distal end portion to the proximal end portion. 28. The method according to claim 23, wherein the one surface portion and the adjacent surface portion branch at a predetermined angle, and the angle gradually decreases in a direction from the distal end portion to the proximal end portion. Blank.